An impedance scanner of the type mentioned initially is known from DE 101 02 204 A1. Electrical impedance scanners such as these are based on the knowledge that malignant tumors have different impedance characteristics than the healthy surrounding tissue so that, when a weak AC voltage (≦5 V) is applied to, or a weak alternating current (≦4 mA) is introduced into, the body by means of the opposing electrode, this changes the electrical field in the region of a tumor, so that this results in a corresponding change in the current density and potential distribution on the skin surface under the probe with the electrode matrix.
By way of example, with an ultrasound appliance as is described in U.S. Pat. No. 5,787,889, an ultrasound record is generally also made in advance or subsequently for more detailed interpretation of the investigation result of such electrical impedance measurements, and this is primarily used to exclude cysts and to localize lesions for biopsy. The ultrasound investigation is itself less specific for the investigation of benign and malignant lesions.
It is not only time-consuming to carry out different investigations successively, but this also has the disadvantage that the association of the results that are in each case found, that is to say the comparability of the respective locations of a problem that has been found, requires further considerable effort.